How To Update Data Using Entity Framework In Visual Studio
First of all add Entity Framework to your solution as shown in the link.
How To Add Entity Framework In Visual Studio
For Updating the Data using Entity Framework follow the below code.

Here TechnomarkEntities is the instance of Entity Model.
Using enclosure do the automatic Connection Open and Close.
First of all create an instance of table row that needs to be updated using Entity Framework.
Assign the new values to the existing row.
Save the updated row to the database using Savechanges method.